The present invention relates to a machine tool for machining workpieces according to the preamble of claim 1.
A machine tool with a grinding device and a workpiece holding device is described in the German utility model no. 201 05 430.2. The workpiece holding device has the disadvantage that, on account of the set-up, there is no possibility of using measuring instruments as are required for precise cylindrical grinding by means of in-process work-size control. The workpiece holding device is therefore not suitable for achieving close manufacturing tolerances. It is also formed such that it can travel between the machining and the workpiece accommodation station. However the travel of the workpiece holding device is significantly longer than would be necessary for the actual machining of the workpiece. This means that the machine tool has a substantially extended machine bed and is accordingly expensive and complicated to produce.
The grinding device according to the above-mentioned utility model comprises two grinding tools, which are fitted to opposite ends of a driven shaft, and is formed so as to be pivotable, so that a workpiece can be machined alternatively by one of the two grinding tools. The disadvantage of this lies in the fact that the grinding tools can only be used in an inclined position, as they could collide with the workpiece holding device if oriented perpendicularly. This means that operations in which the grinding tool has to be oriented perpendicularly, such as the machining of grooves, cannot be carried out. A further disadvantage lies in the fact that the pivotable grinding device requires a considerable amount of space and is expensive.
Moreover, where the machine tool as described in the above-mentioned utility model is concerned, no special measures are provided to protect the grinding and turning tools disposed below the workpiece against accumulations of material arising in the form of chips, for example, when machining a workpiece.